A computer reel is like other reels in that it has a hub, two flanges and stores lengths of windable material. Aside from this rudimentary kinship, the computer reel is vastly set apart. It has evolved its separate way to meet the requirements of a market having unusual scientific and technical sophistication.
A computer reel is used to wind up and pay out magnetic tape in a tape drive system that typically has two reel mounting spindles, a write head, and a read head. To load, a full reel of tape is slipped over one spindle and an empty reel over the other. The end of the tape is threaded past the heads, moistened, and lowered to the hub of the empty reel, where the moistened tape will adhere sufficiently to permit enough winds to be laid down for a gird lock; and the course through which the tape is threaded and passes during the normal operation of the tape drive system may be conveniently referred to as a tape path.
When the drive is energized, the empty reel is torqued by its spindle, causing this reel to take up tape from the other reel, and a winding tension of 8 ounces is automatically maintained.
The system does not have a capstan drive as would be found in audio applications and so is capable of reeling tape at great speed, changing directions in a small fraction of a second. Further, as this tape is transferred back and forth between reels, it is in continuous frictional contact with the respective faces of the read and write heads.